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Allie GI/Renal > 9 - Renal Blood Flow, Nephron Physiology PPT > Flashcards

9 - Renal Blood Flow, Nephron Physiology PPT Flashcards

1
Q

Where does unfiltered blood enter the kidney?

A

Renal artery

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2
Q

Where does filtered blood leave the kidney?

A

Renal vein

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3
Q

If renal blood flow (RBF) increases, what happens to the glomerular filtration rate (GFR)?

A

GFR increases

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4
Q

If renal blood flow (RBF) decreases, what happens to the glomerular filtration rate (GFR)?

A

GFR decreases

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5
Q

How is renal blood flow (RBF) regulated?

A

By increasing or decreasing arteriolar resistance

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6
Q

What two hormones DECREASE renal blood flow by increasing arteriolar resistance?

A
  • Adrenaline (Epinephrine)
  • Angiotensin II
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7
Q

What four hormones INCREASE renal blood flow (RBF) by decreasing arteriolar resistance?

A
  • Atrial Natriuretic Peptide (ANP)
  • Brain (Ventricular) Natriuretic Peptide (BNP or VNP)
  • Prostaglandin
  • Dopamine
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8
Q

What are the two mechanisms of autoregulation of RBF?

A
  1. Myogenic mechanism
  2. Tubuloglomerular mechanism
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9
Q

Describe myogenic mechanism.

A

When stretched by high blood pressure, smooth muscle cells in arterioles automatically contract

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10
Q

Describe tubuloglomerular mechanism.

A

Macula densa releases adenosine which constricts the afferent arteriole when more sodium and chloride ions are detected in distal convoluted tubule.

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11
Q

What’re the two parts of the nephron?

A
  1. Renal corpuscle
  2. Renal tubules
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12
Q

What is the renal corpuscle made up of?

A

GLOMERULUS!

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13
Q

What’s the dang glomerulus made up of?

A

Tuft of capillaries surrounded by a Bowman’s capsule, separated by Bowman’s space (this Bowman guy thinks he’s all that)

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14
Q

How does blood reach the glomerulus? How does it leave?

A

Arrives via afferent arteriole, exits via efferent arteriole

Remember, Arrive Ugly & Exit Fresh (Afferent Unfiltered, Efferent Filtered)

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15
Q

At the efferent arteriole, what does it divide into?

A

Peritubular capillaries that surround the renal tubule

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16
Q

We touched on this briefly in the previous deck, but what is the glomerular filtration barrier?

A

A three-layered structure that separates blood within glomerular capillaries from fluid within the Bowman’s capsule.

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17
Q

What are the three layers of the barrier and what is their purpose?

A
  1. Endothelium
    - made up of glomerular capillary endothelial cells
    - features small pores that allow passage of solutes and some proteins but not RBCs
  2. Basement membrane
    - gel-like layer with tiny pores that block plasma protein passage due to negative charge and size
  3. Epithelium
    - made up of podocytes which wrap around the basement membrane
    - blocks plasma protein passage
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18
Q

GUARANTEED MIDTERM TEST QUESTIONS! What forces affect glomerular filtration?

A

Hydrostatic pressure (fluid) and oncotic pressure (protein), aka the 𝐧𝐞𝐭 𝐮𝐥𝐭𝐫𝐚𝐟𝐢𝐥𝐭𝐫𝐚𝐭𝐢𝐨𝐧 𝐩𝐫𝐞𝐬𝐬𝐮𝐫𝐞.

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19
Q

What are the hydrostatic (HS) and oncotic (OC) pressure locations that affect filtration?

A
  1. HS pressure of blood in glomerular capillary
  2. HS pressure of filtrate in Bowman’s space
  3. OC pressure of proteins in capillary
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20
Q

Delving into the HS BP in the capillary, how does afferent arteriole vasoconstriction affect renal blood flow?

A

It 𝐫𝐞𝐝𝐮𝐜𝐞𝐬 𝐫𝐞𝐧𝐚𝐥 𝐛𝐥𝐨𝐨𝐝 𝐟𝐥𝐨𝐰, which 𝐫𝐞𝐝𝐮𝐜𝐞𝐬 𝐇𝐒 𝐁𝐏 𝐢𝐧 𝐭𝐡𝐞 𝐜𝐚𝐩𝐢𝐥𝐥𝐚𝐫𝐲. (GFR ⬇️)

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21
Q

How does afferent arteriole vasodilation affect renal blood flow?

A

It 𝐢𝐧𝐜𝐫𝐞𝐚𝐬𝐞𝐬 𝐫𝐞𝐧𝐚𝐥 𝐛𝐥𝐨𝐨𝐝 𝐟𝐥𝐨𝐰, which 𝐢𝐧𝐜𝐫𝐞𝐚𝐬𝐞𝐬 𝐇𝐒 𝐁𝐏 𝐢𝐧 𝐭𝐡𝐞 𝐜𝐚𝐩𝐢𝐥𝐥𝐚𝐫𝐲. (GFR ⬆️)

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22
Q

How does efferent arteriole vasoconstriction affect fluid in the glomerular capillary?

A

It 𝐢𝐧𝐜𝐫𝐞𝐚𝐬𝐞𝐬 𝐟𝐥𝐮𝐢𝐝 𝐢𝐧 𝐠𝐥𝐨𝐦𝐞𝐫𝐮𝐥𝐚𝐫 𝐜𝐚𝐩𝐢𝐥𝐥𝐚𝐫𝐲, which 𝐢𝐧𝐜𝐫𝐞𝐚𝐬𝐞𝐬 𝐇𝐒 𝐁𝐏 𝐢𝐧 𝐭𝐡𝐞 𝐜𝐚𝐩𝐢𝐥𝐥𝐚𝐫𝐲. (GFR ⬆️)

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23
Q

How does efferent arteriole vasodilation affect fluid in the glomerular capillary?

A

It 𝐝𝐞𝐜𝐫𝐞𝐚𝐬𝐞𝐬 𝐟𝐥𝐮𝐢𝐝 𝐢𝐧 𝐠𝐥𝐨𝐦𝐞𝐫𝐮𝐥𝐚𝐫 𝐜𝐚𝐩𝐢𝐥𝐥𝐚𝐫𝐲, which 𝐫𝐞𝐝𝐮𝐜𝐞𝐬 𝐇𝐒 𝐁𝐏 𝐢𝐧 𝐭𝐡𝐞 𝐜𝐚𝐩𝐢𝐥𝐥𝐚𝐫𝐲. (GFR ⬇️)

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24
Q

END GUARANTEED MIDTERM QUESTIONS. Continuing, how does urine flow blockage affect the HS filtrate pressure in Bowman’s space?

A

It 𝐢𝐧𝐜𝐫𝐞𝐚𝐬𝐞𝐬 𝐇𝐒 𝐟𝐢𝐥𝐭𝐫𝐚𝐭𝐞 𝐩𝐫𝐞𝐬𝐬𝐮𝐫𝐞 𝐢𝐧 𝐁𝐨𝐰𝐦𝐚𝐧’𝐬 𝐬𝐩𝐚𝐜𝐞 but 𝐧𝐨𝐭𝐚𝐛𝐥𝐲 𝐫𝐞𝐝𝐮𝐜𝐞𝐬 𝐆𝐅𝐑 (inverse relationship). (GFR ⬇️)

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25
Q

An increase in plasma protein concentration can __________ OC protein pressure in the capillary (but GFR ⬇️).

A

INCREASE

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26
Q

A decrease in plasma protein concentration can __________ OC protein pressure in the capillary (but GFR ⬆️).

A

DECREASE

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27
Q

What is GFR based on?

A

The ultrafiltration pressure and capillary permeability.

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28
Q

What’s reabsorption?

A

Retention of substances by moving them from the tubule to the arterioles

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29
Q

What’s absorption?

A

Moving from the tubule to the blood

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30
Q

When does ONLY filtration occur (NO REABSORPTION)?

A

When dealing with products of metabolism like urea or creatine, and foreign substances such as drugs

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31
Q

When does filtration with partial reabsorption occur?

A

When dealing with electrolytes such as sodium or bicarbonate which are easily reabsorbed, and potentially secreted

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32
Q

When does filtration with complete reabsorption occur?

A

When dealing with nutritional substances such as glucose and amino acids

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33
Q

What is a secretion?

A

Any substance not reabsorbed such as organic acids, which are secreted into tubular fluid to become urine. They move from the arterioles to the tubules.

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34
Q

Can filtration remove all substances?

A

NO, but secretion helps to remove almost everything

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35
Q

List four facts about the proximal convoluted tubule!

A
  1. It’s the first renal tube segment
  2. It receives filtrate from the renal corpuscle
  3. It passes filtrate to the loop of Henle
  4. It’s lined by brush border cells
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36
Q

Which structure does the apical surface face and what is it lined with?

A

Faces the lumen and is lined by microvilli for absorption

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37
Q

What structure does the basolateral surface face?

A

Faces the interstitium

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38
Q

What is the prox. convoluted tubule surrounded by that reabsorb/secrete solutes from the blood?

A

The peritubular capillaries

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39
Q

What ions does the prox. convoluted tubule reabsorb into the blood?

A
  • Na+
  • K+
  • Ca2+
  • Cl-
  • Mg2+
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40
Q

Which ion is most important for reabsorption of water and solutes?

A

SODIUM (Na+)

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41
Q

Around ____ of the sodium that gets filtered into the tubular fluid is reabsorbed in the prox. convoluted tubule, and the remaining ____ goes on to the rest of the nephron.

A
  1. 67%
  2. 33%
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42
Q

The tubular fluid has about the same composition as the plasma, so it contains more or less sodium than the tubule cells?

A

MORE sodium

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43
Q

Tubular fluid flows down its concentration gradient and into tubule cells by various channels. What are these channels?

A
  1. Uniport
  2. Symport
  3. Antiport
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44
Q

Symports and antiports are cotransporters, but what does that mean?

A

They can move two or more different solutes at a time

45
Q

The sodium-glucose cotransporter moves sodium in the direction of its _________________ and uses that energy to move glucose into the cell or against its __________________, meaning there’s a higher concentration of glucose already in the cell than the lumen.

A

𝓬𝓸𝓷𝓬𝓮𝓷𝓽𝓻𝓪𝓽𝓲𝓸𝓷 𝓰𝓻𝓪𝓭𝓲𝓮𝓷𝓽

46
Q

Once the glucose enters, it quickly leaves the tubule cell via two channels called…

A

… GLUT1 and GLUT2

47
Q

Where are GLUT1 and GLUT2 located?

A

On the basolateral surface

48
Q

Is this movement of glucose passive or active?

A

PASSIVE- it doesn’t require energy because the glucose concentration in the interstitium and blood is pretty low

49
Q

Where do almost all the filtered glucose, lactate, AAs, phosphate and citrate get reabsorbed into?

A

The prox. convoluted tubule with the help of sodium

50
Q

How is sodium pumped out through the basolateral side and into the intersitium?

A

By a solute pump called the sodium/potassium ATPase!

51
Q

What’s the transfer rate of the sodium/potassium ATPase (as in, the ratio of sodium to potassium)?

A

3 Na+ ions out, 2 K+ ions in (3/2)

52
Q

Why does the sodium/potassium ATPase pump require its ATP?

A

Because it’s pumping both Na+ and K+ against their respective gradients.

53
Q

What keeps the intracellular Na+ level low?

A

The sodium/potassium ATPase pump

54
Q

What’s the result of a low intracellular Na+ level?

A

It allows Na+ to flow into the tubule down its concentration gradient on the apical surface.

55
Q

What happens when Na+ ions get into the interstitium?

A

They diffuse into the capillary down its concentration gradient.

56
Q

What’s the preferred pH level?

A

7.4 pH

57
Q

What cotransporter aids in bicarbonate reabsorption?

A

The Na+/H+ exchanger

58
Q

There’s an important buffer system in the prox. convoluted tubule that deals with carbonic acid. What enzyme splits the carbonic acid into water and CO2?

A

Carbonic anhydrase type 4

Wreck-It-Ralph is the CAT4 because he WRECKS stuff, pretty smart huh

59
Q

Which enzyme facilitates the reverse reaction- making carbonic acid?

A

Carbonic anhydrase type 2

Fix-It-Felix is the CAT2 because he FIXES (or makes) stuff, someone give me an award

60
Q

How much of the filtered bicarbonate is reabsorbed in the prox. convoluted tubule?

A

85%

61
Q

How is roughly 50% of filtered urea reabsorbed?

A

Through diffusion across the cell, down its concentration gradient, and into the capillaries.

62
Q

Is NH4+ (aka ammonium) secreted or reabsorbed?

A

Secreted, it is toxic!

63
Q

On to the loooooop of Henle, where does the loop of Henle receive filtrate from?

A

The prox. convoluted tubule

64
Q

Where does the loop of Henle send the filtrate to?

A

The distal convoluted tubule

65
Q

(TRUE/FALSE): The loop of Henle establishes the osmotic gradient and allows for varying urine conditions.

A

(TRUE)

66
Q

What is the vasa recta?

A

Peritubular capillaries that follow the loop of Henle

67
Q

What’s the osmolarity of tubular fluid leaving the prox. tubule?

A

300 mOsm/L, same as the interstitial fluid around the tubule

68
Q

What are the 6 contents of the tubular fluid?

A
  • Water
  • Sodium
  • Potassium
  • Chloride
  • Calcium
  • Urea
69
Q

What does the osmolarity of the medullary interstitium become as it reaches the bottom of the loop?

A

1200 mOsm/L

70
Q

What is the thin descending portion of the loop of Henle solely permeable to?

A

WATER

71
Q

What is the thick ascending portion of the loop of Henle permeable to?

A
  • Sodium
  • Magnesium
  • Chloride
  • Calcium
  • Bicarbonate
  • Potassium
72
Q

What can enter the thick ascending portion of the loop of Henle?

A

Hydrogen

73
Q

What lines the thin descending portion of the loop to allow only water to pass through?

A

Aquaporin proteins

74
Q

Why don’t solutes leave the tubular fluid in large quantities?

A

There’s just very few channels for them to exit through, this is by design. It’s to keep them concentrated while removing the wata

75
Q

The thin ascending limb is ____________ to water.

A

Impermeable

76
Q

What channels does the thin ascending limb have in abundance?

A

Sodium and chloride channels

77
Q

As the tubular fluid travels up the thin ascending limb, what osmolarity will it reach at the top of the thin ascending limb?

A

600 mOsm/L

78
Q

What makes the thick ascending limb thicc?

A

Being made up of cuboidal epithelium instead of squamous cells.

79
Q

Cuboidal cells don’t contain aquaporin, so what does this mean for the thick ascending limb?

A

It is IMPERMEABLE to WATER!

80
Q

What will the osmolarity be at the top of the thick ascending limb and why?

A

325 mOsm/L because solutes continue to move out of that splendid tubular fluid

81
Q

What is the process of creating this osmolarity gradient called? No, not Bob.

A

Countercurrent multiplication

82
Q

How does countercurrent multiplication work?

A

It uses ATP to build up the concentration gradient and reabsorb water into the interstitial fluid via passive diffusion.

83
Q

How is the distal convoluted tubule (DCT) different from the proximal convoluted tubule?

A

The DCT is more hormonally controlled therefore more precise and accurate

84
Q

Where does the DCT receive filtrate from?

A

The loop of Henle

85
Q

Where does the DCT send filtrate?

A

The collecting duct

86
Q

The DCT is composed of ________ and _________ portions

A
  1. Early
  2. Late
87
Q

What is the DCT lined with?

A

Brush border cells

88
Q

The early portion of the DCT is ____________ to water

A

IMPERMEABLE

89
Q

What is the early portion of the DCT permeable to?

A
  • Na+
  • Cl-
  • Ca2+
  • Mg2+
90
Q

What’s the late portion of the DCT permeable to?

A
  • Na+
  • Cl-
  • ADH
  • H2O
  • HCO3-
  • K+
91
Q

What can enter the late DCT?

A

H+ and K+

92
Q

There is a Na+/Cl- cotransporter present on the apical surface of the early DCT. What does it function to do?

A

It moves 1 sodium and 1 chloride ion into the cell! Sodium will be moved along its gradient, and chloride will be moved against its gradient. Chloride will then leave through the Cl- channels on the basolateral side and go down its gradient.

93
Q

Similarly to the Cl- channels on the basolateral surface, there are ____ channels on the apical surface of the DCT alongside _______ channels on the basolateral surface of the tubule cells.

A
  1. Ca2+
  2. Na+/Ca2+
94
Q

Calcium reabsorption is regulated by what hormone that is secreted by the parathyroid glands?

A

Parathyroid hormone

95
Q

What’s the effect of parathyroid hormone binding to tubule cells?

A

Reabsorption of calcium increases

96
Q

In the late DCT and collecting duct, what cells are dispersed among the tubule cells?

A

Principal and alpha-intercalated cells

97
Q

How do alpha-intercalated cells remove H+ ions?

A

They pump them across the apical surface and into the lumen of the nephron.

98
Q

What is the medullary collecting duct permeable to?

A
  • Na+
  • Cl-
  • ADH
  • H2O
  • Urea
  • HCO3-
99
Q

What can enter the medullary collecting duct?

A

H+ ions

100
Q

Within the DCT, there is a net movement of _________ and __________ into the blood, while H+ is pushed into the tubule.

A
  1. Sodium
  2. Chloride
101
Q

What hormone regulates the DCT and collecting duct?

A

Aldosterone, which is made in the adrenal cortex

102
Q

What does aldosterone trigger after diffusing across the membrane of principal cells?

A

It triggers the increased synthesis of the ATP-dependent potassium pump and Na+/K+ ATPase transporter.

103
Q

What do the two aldosterone-triggered pumps accomplish?

A

They increase Na+ absorption and K+ secretion.

104
Q

Refresh: What does parathyroid hormone seek to help absorb?

A

Calcium

105
Q

Refresh: When the body wants to retain water, what does the pituitary gland secrete?

A

ADH

106
Q

ADH binds to principal cells via a _________ receptor, then triggers the vesicles contain aquaporin 2 to bind to the basolateral and apical membranes.

A

protein

107
Q

What does ADH’s activation of the aquaporin 2 vesicles accomplish?

A

It allows water to rapidly cross the apical membrane and get into the cell, then continue across the basolateral membrane into the interstitium and nearby peritubular capillaries.

108
Q

This process of osmosis shifts water from the _________ back into ___________.

A
  1. Lumen
  2. Circulation

LAST CARD GOOD JOB!! It is currently 1:08am Aug 20, 2024

Allie GI/Renal (18 decks)

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